1. Field of the Invention
The present invention relates to an industrial robot, and in particular, to an industrial robot provided with a fixed body, a movable body movably attached to the fixed body, and an electric cable connected between the fixed body and the movable body for electric power supply and for communication of control of a tool attached to the movable body.
2. Description of the Related Art
A conventional prior art such as disclosed in Japanese unexamined patent publication No. 10-217179 introduces such a robot that comprises a carriage movable in at least one plane direction and a rotatable arm mounted on the carriage. This robot comprises a tool in the arm, and makes the arm rotate to provide operations on a work using the tool, after moving the carriage to a position. Accordingly, this robot has to have a power supply line for electrically connecting the arm and a power source, as well as a signal line for connecting the arm and a controller. This required an electric cable to be placed between the arm and a fixed body, allowing them to move in relative directions.
Generally, the Cableveyers (registered trademark) have been used in cable connections between the fixed bodies and the movable bodies of robots. The Cableveyer consists of a plurality of frames made of synthetic resin and the like that are flexibly connected with one another by pins, and includes a plurality of cables inside the frames. This structure allows the cables to freely bend under a protection of the frames, as the movable body moves, and consistently provides electric power and signals to the movable body.
However, the Cableveyer provided with the frames took a lot of space, which causes a device to be large in size. Further, the cables scrape against the frames as the fixed body and the movable body moved in the relative directions producing abrasion powder of the cables' covers and the frames. Removing the abrasion powder was troublesome.
The aforementioned conventional prior art, therefore, uses a flat cable in a cable connection between the fixed body and the movable body. The flat cable consists of a plurality of cables connected in parallel, and bends freely. The use of the flat cable in replacement of the Cableveyer allows the device to be small in size, and can inhibit the abrasion powder, which is produced by the friction between the cables and frames, from being produced.
The above-mentioned conventional prior art using the flat cable can make the device small in size and can restrain the generation of the abrasion powder caused by the friction of the Cableveyer. However, the flat cable in the conventional prior art can bend freely without any restriction due to its original flexible nature, as the movable body moves relative to the fixed body.
This causes a bent portion of the flat cable to interfere with an obstacle and damages the flat cable, because, unlike the Cableveyer, the flat cable is exposed and is unprotected by a cover.